This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The purpose of this study was to test whether long-term pair housing of male rhesus macaques ameliorated negative responses to stressful events that can occur in the course of routine husbandry or research procedures. Methods:[unreadable]Twelve singly housed individuals were videotaped during two potentially stressful events before and after social introduction into pairs. During each stressor, abnormal behavior and anxiety-related behavior were quantified from videotape. Results/Conclusion:[unreadable]When visually exposed to the restraint and anesthesia of other monkeys, subjects showed significantly reduced frequencies of abnormal behavior when pair-housed in comparison to their reactions when housed singly. Noisy and disruptive conversation between technicians standing immediately in front of the subjects'cage did not elicit the same reduction in abnormal behavior. Neither test showed a significant difference across housing settings for anxiety-related behaviors.[unreadable]These findings suggest that pair housing buffers adult male rhesus macaques against common stressors in the laboratory setting.